Are Your Kids Wearing Your Genes?

Bounding through the door into the bright California sunshine with his dog, my son, Matthew, laughed as the basset took off at full speed toward a cliffside meadow of wildflowers.

"Sophie!" Matthew called out loudly. "So-o-o-o-o-phie!"

He sounded just like my father. A hint of command. A wealth of love. A trace of "get over here before I drop you off at the pound."

I watched him as he walked toward the cliff and snapped the leash on his hound. It was like studying a composite image of my family. He has my dad's shoulders, my mother's upper lip, my husband's incredible eyes and, if the dog trampling the flowers at his feet was any indication, my passion for stray mutts with big brown eyes.

But as I stood there, one thing occurred to me: Just what other things might we have passed along without knowing it?

Are There Stubborn Genes?

In addition to things such as a propensity for heart disease or high blood pressure—among the thousands of predilections that have a genetic basis—what I really worried about my son getting is what my husband's family calls "The Stubborn Gene." Try to get someone with it to do something a teensy bit differently than he wants, and he'll just calmly shake his head from side to side. It is not a gene that's conducive to good family relationships.

Researcher Thomas J. Bouchard Jr., PhD, director of the Minnesota Study of Twins Reared Apart at the University of Minnesota, chuckles when I tell him my fears. "You really can't say whether or not a child has inherited one trait or another on an individual basis," says Bouchard, who has spent decades looking into twins reared apart and twins reared together to answer exactly that question. But in general, population studies suggest that almost every psychological trait a child has is only about 50% inherited and 50% shaped by environment.

What that means is that even if the family has a genetic predisposition to stubbornness, there's only a small chance that my kid will be as stubborn as his father. That news cheers me up considerably. [pagebreak]

DNA Is Not Destiny

Certain traits and disorders do seem to run in families, says geneticist Kathleen Merikangas, PhD, who heads the developmental genetic epidemiology section for the National Institute of Mental Health. But evidence suggests that the most common health problems, such as heart disease, aren't determined by single genes alone. And when all is said and done, it's likely that scientists will find that single genes don't determine behavior or personality traits, or disorders such as depression and anxiety either.

Instead, says Merikangas, researchers are more likely to find that children develop certain traits and disorders just like they develop common health problems such as heart disease—when two things happen. First, a gene or group of genes makes the child vulnerable. Then something from his environment—the death of a parent, a life-threatening illness, living on Big Macs—sets the genes in motion, and the trait or health problem emerges.

The idea that what happens to us outside our bodies can affect the genes inside may seem radical, but there's increasing evidence that what happens to you and how you react is communicated back to genes by a complex sequence of chemical reactions. "We now know that genes are beautifully designed to respond to the environment," explains Merikangas. Events outside the body influence which genes are switched on and off in cells and what they do. Nowhere is this more evident than in the common diseases that eventually do us in. "Heart disease, lung disease, high blood pressure, high cholesterol, even cancer—all are conditioned upon interactions between genes and environmental factors," says Aubrey Milunsky, MD, DSc, director of the Center for Human Genetics at Boston University School of Medicine. Like a bunch of rowdy kids who aren't too bad when they're by themselves, the genes involved in these diseases can be big trouble when they get together—especially when they're activated by a fatty diet, lots of stress, or the life of a couch potato.

Take cholesterol. "Most of the 20 to 30 genes identified in cholesterol metabolism contribute in one way or another to the body's handling of the substance," says geneticist Wylie Burke, MD, PhD, who chairs the department of medical history and ethics at the University of Washington. "But what you inherit is the likelihood that your cholesterol level will fall within a certain range—high end, low end, or somewhere in between. Whether you actually show up in the high end or the low end is profoundly influenced by the kind of diet you eat." Pig out on bacon cheeseburgers every day, and—unless you're one of those rare individuals with fat-tolerant genes—you're in trouble. [pagebreak]

Making Choices

Although the majority of common disorders such as heart disease are caused by the interaction of multiple genes and the environment, others are caused by single-gene defects that have been passed from parent to child. These single-gene disorders are divided into several categories.

Dominantly inherited conditions such as Huntington's disease or polycystic kidney disease. If you carry the genetic glitch responsible for these conditions, there's a 50 percent possibility you'll pass it to your kid.

Recessively inherited conditionssuch as cystic fibrosis or sickle cell anemia. If both you and your partner have the genes responsible for these disorders, your children will have a one in four chance of being affected.

Sex-linked inherited conditionssuch as color blindness. A mother who has the gene has a 50-50 chance of passing it to a male child, who will become color-blind, or to a female child, who will become a carrier (unless her father is color-blind, in which case she will be too).

Although medical science is far from being able to cure most single-gene conditions, an increasing number of them can be detected and virtually eradicated. But it comes at a price. People who carry single-gene disorders such as Tay-Sachs disease, a degenerative brain disorder caused by the combination of a recessive gene from each parent, may need to forgo having their own biological children or decide after prenatal genetic testing whether they want to continue with a pregnancy.[pagebreak]

Beat Your Bad Genes

If you suspect there's a genetic disorder running through your family, you can do something about it. Here's how researchers suggest you get started:

Climb the family tree "The most critical item is your family history," says Milunsky. "Everybody should have as detailed a knowledge of their own family history as possible. All medical records in doctors' offices should open with a pedigree of that person's family on the first page."

Unfortunately, doctors don't take the time these days to take an extensive family history. Instead, patients are simply asked to fill out a short questionnaire that, by its very brevity, seems to imply that family history is not important. One study showed that doctors spend an average of only 2.5 minutes talking about family history with their patients. And perhaps as a result, new research from Northwestern University finds that doctors fail to recognize that 20% of their patients are at increased risk for a genetic disease.

So chart your own family tree, outlining as best you can four generations of births, deaths, stillbirths, birth defects, sudden deaths, deafness, recurrent miscarriages, retardation, and genetic or suspected genetic diseases. Take it to your family doctor, and make sure she looks at it when discussing your health.

Consider your ethnic heritage "After you've drawn your family tree, look at your ethnic origins," says Milunsky. "People don't materialize in the doctor's office and say, 'My main complaint is that I'm Italian, or Irish, or Jewish,'" but maybe they should. There's a systematic ignoring that goes on about people's ethnicity, yet each of us, by virtue of our origins, carries a particular ethnic or genetic burden.

"Name the group, and there's an association," he says. If you're Caucasian, for example, there's a 1 in 25 likelihood that you carry a gene mutation for cystic fibrosis, a disease that clogs the lungs with mucus. Caucasians, on average, also have 1 in 25 odds of carrying a mutation of the factor V Leiden gene, which predisposes them to sudden death and strokes from blood clots. If you're African-American, there's a 1 in 12 likelihood that you carry a sickle cell gene mutation, which causes life-threatening anemia and extreme pain if one has inherited that gene mutation from both parents. If you're Armenian, Turkish, Arabic, or Sephardic Jew, there's a 1 in 8 likelihood that you carry the gene mutation for familial Mediterranean fever, a condition that causes inflammation throughout the body, followed by kidney failure.[pagebreak]

Talk to a geneticist Most doctors who graduated even 10 to 15 years ago are simply not up to speed on the rapid advances in genetics, says Milunsky. According to 2003 survey, only 13% of internists, 21% of OB/GYNs, and 40% of oncologists know the facts about genes and breast cancer. Since breast cancer genetics have been the most widely publicized of all disease-associated genetics, that's a pretty shocking lapse—especially among the OB/GYNs and oncologists.

"If there are reasons for concern on your family tree—multiple cancers, different cancers, early heart attacks, say in the 40s or even the early 50s—then you should have a consultation with a board-certified clinical geneticist," advises Milunsky. "It may save your life." If your doctor does not know a local medical geneticist, go online to the American Board of Medical Genetics Web site.

Get a carrier blood test If you have a recessive genetic mutation, you're unlikely to get sick, but if you have a baby with someone who has the same mutation, that child will develop the disorder, says Milunsky. You should request a blood test to see if you carry the gene for disorders that characteristically occur in your ethnic or racial group before you have children.

Accept children for who they are "Children are born with a range of reactions to the world," says Merikangas. And what you do at home can influence how your child's genetic heritage is expressed and how he functions as an adult. Take shyness, for example. Push a shy child into public speaking, or demand that he participate in class, and you may boost the odds that he will become withdrawn as an adult. Accept the child as he is, and help him take gradual steps toward group involvement, and he may adapt and do well.

Muster resources If a particular problem seems to run in your family, be prepared to get help for your child, says Merikangas. Children who have a parent with a history of drug or alcohol abuse, for example, are significantly more likely to develop the problem themselves. "If you have this in your family, go to a professional counselor, maybe at your child's school, and ask, 'What are the signs that my child is in trouble? How can I tell if my child is developing this problem? Where can I get help if he is?'"

The same thing applies to children of parents who have depression or any other condition with a heritable component. "Twenty percent of these kids may develop the same disorder as their parents," says Merikangas. So you have to be proactive. Learn the risk factors for whatever's putting your child at risk, watch for the signs, and be prepared to take action. Remember, modifying your child's environment—enriching his opportunities or putting him in a more stable school, for example—can change how the genes you've handed him affect his life.

Don't ignore the obvious "If we live the way we're supposed to, we automatically minimize our genetic risks," says Burke. If you encourage your kids to eat less fat and more fish and vegetables, exercise daily, maintain a healthy weight, avoid smoke, and reduce stress, they're automatically at lessened risk. If, as adults, they get regular health screenings for heart disease, colon cancer, breast cancer, and the like, they're at lower risk of getting or dying from these diseases. And if you work with your family doctor to take preventive action, you will have done everything you can do to give your kids a happy, healthy life. Whatever their genes.